According to the spec sheet, Google Glass will offer one full day of battery life for normal usage, but features like Hangouts and video recording will expend the battery faster. Google recommends recharging the kit with with the Micro USB cable and charger it supplies with Glass.

The display resolution is the "equivalent of a 25-inch high definition screen from eight feet away", but Google is being no more specific than that.

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The head mountable device comes with 16GB Flash onboard storage of which 12GB of is useable and is synced with Google cloud storage. Glass is tied to a Google account and automatically uploads location data along with video and photos to a Google+ Instant Upload album, according to the Glass Terms of Service.

The camera takes photos at five megapixels and video at 720p, while audio relies on a Bone Conduction Transducer system that does away with the need for earphones by transmitting audio directly to the user's skull. It's unclear where the system is located.

Google filed a patent for the system in January, noting that the transducer transmits vibrations from an audio signal source on the device to the frame before reaching the wearer. "The vibration transducer vibrates the head-mounted display without directly vibrating a wearer. However, the head-mounted display structure vibrationally couples to a bone structure of the wearer, such that vibrations from the vibration transducer may be indirectly transferred to the wearer's bone structure," it wrote.

Glass connectivity options include the wi-fi standard 802.11b/g and Bluetooth. While it supports any Bluetooth-capable phone, the MyGlass app, which enables GPS and SMS, is currently only available for Android 4.0.3 (Ice Cream Sandwich and higher). It's also the app that Glass owners use to configure and manage the device.

Glass has an adjustable nosepad and extra nosepads in two sizes. It also comes with a Glass pouch and like a smartphone, users should keep it away from liquids, Google notes in the FAQ.

"As you probably know, most states have passed laws limiting the use of mobile devices while driving any motor vehicle, and most states post those rules on their department of motor vehicles websites. Read up and follow the law! Above all, even when you're following the law, don't hurt yourself or others by failing to pay attention to the road. The same goes for bicycling: whether or not any laws limit your use of Glass, always be careful."

Glass is not for everyone either. It warns that just like normal glasses, some people feel eye strain or get a headache, and advises against children under 13 wearing them since it could harm developing vision.